1,317 research outputs found

    Co-existence of organising pneumonia in a patient with Mycobacterium Avium Intracellulare pulmonary infection

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    Non-tuberculous mycobacterias (NTMs) have many clinical manifestations in humans, depending on the underlying immunological status. We present a patient with Mycobacterium avium intracellulare pulmonary infection and co-existing, biopsy proven non-granulomatous organising pneumonia in distinct regions within the lungs. Treatment consisting of anti-mycobacterial therapy and corticosteroids led to clinico-radiological resolution. This case represents a potential broader clinico-pathological manifestation of Mycobacterium avium intracellulare

    A Honeycomb Proportional Counter for Photon Multiplicity Measurement in the ALICE Experiment

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    A honeycomb detector consisting of a matrix of 96 closely packed hexagonal cells, each working as a proportional counter with a wire readout, was fabricated and tested at the CERN PS. The cell depth and the radial dimensions of the cell were small, in the range of 5-10 mm. The appropriate cell design was arrived at using GARFIELD simulations. Two geometries are described illustrating the effect of field shaping. The charged particle detection efficiency and the preshower characteristics have been studied using pion and electron beams. Average charged particle detection efficiency was found to be 98%, which is almost uniform within the cell volume and also within the array. The preshower data show that the transverse size of the shower is in close agreement with the results of simulations for a range of energies and converter thicknesses.Comment: To be published in NIM

    Exotic bulk viscosity and its influence on neutron star r-modes

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    We investigate the effect of exotic matter in particular, hyperon matter on neutron star properties such as equation of state (EoS), mass-radius relationship and bulk viscosity. Here we construct equations of state within the framework of a relativistic field theoretical model. As hyperons are produced abundantly in dense matter, hyperon-hyperon interaction becomes important and is included in this model. Hyperon-hyperon interaction gives rise to a softer EoS which results in a smaller maximum mass neutron star compared with the case without the interaction. Next we compute the coefficient of bulk viscosity and the corresponding damping time scale due to the non-leptonic weak process including Λ\Lambda hyperons. Further, we investigate the role of the bulk viscosity on gravitational radiation driven r-mode instability in a neutron star of given mass and temperature and find that the instability is effectively suppressed.Comment: 5 pages, 3 figure, presented in the Conference on Isolated Neutron Stars: From the Interior to The Surface, London, UK, 24-28 April, 2006; revised and final version to appear in Astrophys. Space Sc

    What are communities of practice? A comparative review of four seminal works

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    This paper is a comparative review of four seminal works on communities of practice. It is argued that the ambiguities of the terms community and practice are a source of the concept's reusability allowing it to be reappropriated for different purposes, academic and practical. However, it is potentially confusing that the works differ so markedly in their conceptualizations of community, learning, power and change, diversity and informality. The three earlier works are underpinned by a common epistemological view, but Lave and Wenger's 1991 short monograph is often read as primarily about the socialization of newcomers into knowledge by a form of apprenticeship, while the focus in Brown and Duguid's article of the same year is, in contrast, on improvising new knowledge in an interstitial group that forms in resistance to management. Wenger's 1998 book treats communities of practice as the informal relations and understandings that develop in mutual engagement on an appropriated joint enterprise, but his focus is the impact on individual identity. The applicability of the concept to the heavily individualized and tightly managed work of the twenty-first century is questionable. The most recent work by Wenger – this time with McDermott and Snyder as coauthors – marks a distinct shift towards a managerialist stance. The proposition that managers should foster informal horizontal groups across organizational boundaries is in fact a fundamental redefinition of the concept. However it does identify a plausible, if limited, knowledge management (KM) tool. This paper discusses different interpretations of the idea of 'co-ordinating' communities of practice as a management ideology of empowerment

    Differential cross sections, charge production asymmetry, and spin-density matrix elements for D*(2010) produced in 500 GeV/c pi^- nucleon interactions

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    We report differential cross sections for the production of D*(2010) produced in 500 GeV/c pi^- nucleon interactions from experiment E791 at Fermilab, as functions of Feynman-x (x_F) and transverse momentum squared (p_T^2). We also report the D* +/- charge asymmetry and spin-density matrix elements as functions of these variables. Investigation of the spin-density matrix elements shows no evidence of polarization. The average values of the spin alignment are \eta= 0.01 +- 0.02 and -0.01 +- 0.02 for leading and non-leading particles, respectively.Comment: LaTeX2e (elsart.cls). 13 pages, 6 figures (eps files). Submitted to Physics Letters

    Transient deformation associated with explosive eruption measured at Masaya volcano (Nicaragua) using Interferometric Synthetic Aperture Radar

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    Deformation caused by processes within a volcanic conduit are localised, transient, and therefore challenging to measure. However, observations of such deformation are important because they provide insight into conditions preceding explosive activity, and are important for hazard assessment. Here, we present measurements of low magnitude, transient deformation covering an area of ∼4 km2 at Masaya volcano spanning a period of explosive eruptions (30th April - 17th May 2012). Radial uplift of duration 24 days and peak displacements of a few millimetres occurred in the month before the eruption, but switched to subsidence ∼27 days before the onset of the explosive eruption on 30th of April. Uplift resumed during, and continued for ∼16 days after the end of the explosive eruption period. We use a finite element modelling approach to investigate a range of possible source geometries for this deformation, and find that the changes in pressurisation of a conduit 450 m below the surface vent (radius 160 m and length 700 m), surrounded by a halo of brecciated material with a Young’s modulus of 15 GPa, gave a good fit to the InSAR displacements. We propose that the pre-eruptive deformation sequence at Masaya is likely to have been caused by the movement of magma through a constriction within the shallow conduit system. Although measuring displacements associated with conduit processes remains challenging, new high resolution InSAR datasets will increasingly allow the measurement of transient and lower magnitude deformation signals, improving the method’s applicability for observing transitions between volcanic activity characterised by an open and a closed conduit system

    アデノシルコバラミン関与ジオールデヒドラターゼの再活性化因子に関する研究

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    OBJECTIVE: To determine the extent to which prostheses with no readily available evidence to support their use are being implanted in primary total hip arthroplasty. DESIGN: Systematic review of the literature. DATA SOURCES: The 9th annual report of the National Joint Registry of England and Wales (NJR) was analysed to identify prostheses with an Orthopaedic Data Evaluation Panel rating of "unclassified" or "pre-entry" used in primary total hip arthroplasty in 2011. A systematic review of those prostheses was carried out using PubMed, Cochrane, Embase, OVID, and Google databases. STUDY SELECTION: Prostheses used in primary total hip arthroplasty as published in the NJR's 9th annual report were analysed. Only literature that included the name of the prosthesis was included. Literature yielded in the search results was excluded if it reported animal, non-orthopaedic, non-total hip arthroplasty, or non-device related studies. RESULTS: The systematic review found that 24% (57/235) of all hip replacement implants available to surgeons in the UK have no evidence for their clinical effectiveness. It also shows that 10,617 (7.8%) of the 136,593 components used in primary hip replacements in 2011 were implanted without readily identifiable evidence of clinical effectiveness. These comprised 157 cemented stems (0.5% of 34,655 implanted), 936 (2.8% of 33,367) uncemented stems, 1732 (7.1% of 24,349) cemented cups, and 7577 (17.1% of 44,222) uncemented cups. CONCLUSIONS: This study shows that a considerable proportion of prostheses available to orthopaedic surgeons have no readily available evidence of clinical effectiveness to support their use. Concern exists about the current system of device regulation, and the need for a revised process for introducing new orthopaedic devices is highlighted

    Longitudinal double-spin asymmetry and cross section for inclusive neutral pion production at midrapidity in polarized proton collisions at sqrt(s) = 200 GeV

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    We report a measurement of the longitudinal double-spin asymmetry A_LL and the differential cross section for inclusive Pi0 production at midrapidity in polarized proton collisions at sqrt(s) = 200 GeV. The cross section was measured over a transverse momentum range of 1 < p_T < 17 GeV/c and found to be in good agreement with a next-to-leading order perturbative QCD calculation. The longitudinal double-spin asymmetry was measured in the range of 3.7 < p_T < 11 GeV/c and excludes a maximal positive gluon polarization in the proton. The mean transverse momentum fraction of Pi0's in their parent jets was found to be around 0.7 for electromagnetically triggered events.Comment: 6 pages, 3 figures, submitted to Phys. Rev. D (RC

    Measurement of the Hadronic Photon Structure Function F_2^gamma at LEP2

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    The hadronic structure function of the photon F_2^gamma is measured as a function of Bjorken x and of the factorisation scale Q^2 using data taken by the OPAL detector at LEP. Previous OPAL measurements of the x dependence of F_2^gamma are extended to an average Q^2 of 767 GeV^2. The Q^2 evolution of F_2^gamma is studied for average Q^2 between 11.9 and 1051 GeV^2. As predicted by QCD, the data show positive scaling violations in F_2^gamma. Several parameterisations of F_2^gamma are in agreement with the measurements whereas the quark-parton model prediction fails to describe the data.Comment: 4 pages, 2 figures, to appear in the proceedings of Photon 2001, Ascona, Switzerlan
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